Flash content displays and works correctly for me for varying amounts of time, but eventually it always freezes and goes blank. On youtube in particular. i can usually catch no more than 30 seconds of a video without it doing that. Other sites, like pandora, last a lot longer. Any ideas what this could be?

I've been having similar problems with watching videos on various websites and found going into "Add-Ons" in Firefox and disabling Real Player, I get noticeably better performance. Maybe you'll have similar luck. Not a 100% fix but it is better than before.